U.S. patent application number 11/589769 was filed with the patent office on 2007-05-03 for apparatus and method for controlling operation of reciprocating compressor.
This patent application is currently assigned to LG Electronics Inc.. Invention is credited to Kyung-Bum Heo.
Application Number | 20070098566 11/589769 |
Document ID | / |
Family ID | 37996530 |
Filed Date | 2007-05-03 |
United States Patent
Application |
20070098566 |
Kind Code |
A1 |
Heo; Kyung-Bum |
May 3, 2007 |
Apparatus and method for controlling operation of reciprocating
compressor
Abstract
An apparatus and method for controlling an operation of a
reciprocating compressor are disclosed. The apparatus for
controlling an operation of a reciprocating compressor includes: a
TDC/BDC detecting unit for detecting a TDC and a BDC of the
reciprocating compressor; and a controller for independently
controlling the TDC and the BDC so as to fit each reference
position based on the detected TDC and BDC. Efficiency of the
reciprocating compressor can be enhanced by independently
controlling a top dead center and a bottom dead center.
Inventors: |
Heo; Kyung-Bum;
(Gwangmyeong, KR) |
Correspondence
Address: |
KED & ASSOCIATES, LLP
P.O. Box 221200
Chantilly
VA
20153-1200
US
|
Assignee: |
LG Electronics Inc.
|
Family ID: |
37996530 |
Appl. No.: |
11/589769 |
Filed: |
October 31, 2006 |
Current U.S.
Class: |
417/44.1 |
Current CPC
Class: |
F04B 35/045 20130101;
F04B 49/065 20130101; F04B 2201/0206 20130101 |
Class at
Publication: |
417/044.1 |
International
Class: |
F04B 49/06 20060101
F04B049/06 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 1, 2005 |
KR |
103932/2005 |
Claims
1. An apparatus for controlling an operation of a reciprocating
compressor comprising: a top dead center (TDC)/bottom dead center
(BDC) detecting unit for detecting a TDC and a BDC of the
reciprocating compressor; and a controller for independently
controlling the TDC and the BDC according to each reference
position based on the detected TDC and BDC.
2. The apparatus of claim 1, wherein the controller controls the
TDC to fit the first reference position based on the detected TDC
and BDC and then independently controls the BDC to fit a second
reference position.
3. The apparatus of claim 1, wherein the controller controls the
BDC to fit the second reference position based on the detected TDC
and BDC and then independently controls the TDC to fit the first
reference position.
4. The apparatus of claim 1, wherein the controller controls the
TDC to fit the first reference position based on the detected TDC
and BDC and then independently and simultaneously controls the BDC
to fit a second reference position.
5. The apparatus of claim 1, wherein the controller independently
controls a TDC firing angle and a BDC firing angle to make the TDC
fit the first reference position and the BDC fit the second
reference position.
6. The apparatus of claim 1, wherein the controller comprises:
voltage and current detection units for detecting voltage applied
to the reciprocating compressor and current flowing at the
reciprocating compressor; a microcomputer for calculating a stroke
estimate value based on the detected voltage and current, and
outputting a switching control signal based on a result obtained by
comparing the calculated stroke estimate value and a stroke command
value; and a switch switched on or off according to the outputted
control signal to control the TDC or BDC.
7. The apparatus of claim 1, wherein the reference position is
previously set in the form of a look-up table in a storage
unit.
8. The apparatus of claim 1, wherein the reference position is
calculated by the microcomputer based on the TDC and the BDC
detected according to an initial initiation and previously stored
in the storage unit.
9. The apparatus of claim 6, wherein the switch is a thyrister for
controlling a flow of current according to the switching signal and
input AC power.
10. A method for controlling an operation of a reciprocating
compressor comprising: detecting a top dead center (TDC) and a
bottom dead center (BDC) of a piston of the reciprocating
compressor (a first step); and independently controlling the TDC or
the BDC of the piston of the reciprocating compressor according to
first and second reference positions, respectively (a second
step).
11. The method of claim 10, wherein the first step comprises: when
the TDC does not fit the first reference position, reducing the TDC
and BDC firing angles.
12. The method of claim 10, wherein the second step comprises: a
first TDC control step of first controlling the TDC of the piston
of the reciprocating compressor so as to fit the first reference
position; and a first BDC control step of controlling the BDC so as
to fit the second reference position, when the TDC of the piston
fits the first reference position.
13. The method of claim 10, wherein the second step comprises: a
second BDC control step of first controlling the BDC of the piston
of the reciprocating compressor so as to fit the second reference
position; and a second TDC control step of controlling the TDC of
the piston so as to fit the first reference position, when the BDC
of the piston fits the second reference position.
14. The method of claim 10, wherein the second step comprises: a
third TDC control step of controlling the TDC of the piston of the
reciprocating compressor so as to fit the first reference position;
and simultaneously and independently controlling the BDC of the
piston so as to fit the second reference position.
15. The method of claim 10, wherein the second step comprises: when
the BDC does not fit the desired position, increasing the TDC
firing angle and reducing the BDC firing angle.
16. The method of claim 15, wherein the TDC and the BDC have values
which are in inverse proportion to the size of the TDC and BDC
firing angles.
17. The method of claim 15, wherein a value of the BDC firing angle
being 1o reduced is smaller than a value of the TDC firing value
being increased.
18. The method of claim 12, wherein in adjusting the TDC so as to
fit the first reference position, the TDC is controlled to be zero.
Description
RELATED APPLICATION
[0001] The present disclosure relates to subject matter contained
in priority Korean Application No. 10-2005-0103932, filed on Nov.
1, 2005, which is herein expressly incorporated by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an apparatus and method for
controlling an operation of a reciprocating compressor and, more
particularly, to an apparatus and method for controlling an
operation of a reciprocating compressor capable of independently
controlling top and bottom dead centers.
[0004] 2. Description of the Related Art
[0005] In general, a reciprocating compressor can vary compression
capacity by changing a compression ratio of a reciprocating
compressor by controlling a voltage applied to a motor within the
compressor.
[0006] The reciprocating compressor will be described in detail
with reference to FIG. 1
[0007] FIG. 1 is a schematic block diagram showing an apparatus for
controlling operations of a reciprocating compressor according to a
related art.
[0008] As shown in FIG. 1, the related art apparatus for
controlling an operation of a reciprocating compressor includes a
reciprocating compressor having certain compression capacity as a
piston positioned therein moves in a vertical direction by a
voltage that controls a stroke according to a stroke command value
(stroke reference value); a voltage detection unit 12 for detecting
a voltage applied to the reciprocating compressor; a current
detection unit 11 for detecting current flowing at the
reciprocating compressor; a microcomputer 13 for calculating the
stroke estimate value based on the detected voltage and current,
and outputting a switching control signal based on the comparison
result of the calculated stroke estimate value and the stroke
command value; and a triac (Tr1) switched on or off according to
the switching control signal to thus control a flow of current of
general AC input power source.
[0009] The apparatus for controlling an operation of the
reciprocating compressor controls a motor of the reciprocating
compressor by turning on or off general AC input power (AC 220V) by
controlling an ON/OFF operation of the triac Tr1.
[0010] Herein, because the general AC input power is an AC voltage,
voltage (positive (+) voltage) of one half period of the general AC
input power is used to control a position of a top dead center
(TDC) of the piston and voltage (negative (-) voltage) of the other
half period of the general AC input power is used to control a
position of a bottom dead center (BDC) of the piston.
[0011] The TDC refers to a position of an upper surface of the
piston when the reciprocating compressor performs a suction stroke
(namely, when the piston is lifted up to its maximum level. The BDC
refers to a position of the upper surface of the piston when the
reciprocating compressor is in a suction stroke (namely, when the
piston is lowered to its maximum level. The distance between the
TDC and BDC is called a stroke.
[0012] Based on the position of an initial state of the piston, as
an amount of voltage (+ voltage) of one half period increases, the
TDC is raised, and as an amount of voltage of the other half period
increases, the BDC is lowered.
[0013] Herein, a time point at which the triac Tr1 is turned on to
supply the voltage (+) voltage of one half period to control the
TDC is called a TDC firing angle, and a time point at which the
triac Tr1 is turned on to supply the voltage (- voltage of the
other half period to control the BDC is called a BDC firing
angle.
[0014] The related art apparatus and method for controlling an
operation of the reciprocating compressor has a problem that the
TDC and BDC cannot be independently controlled because the TDC
firing angle and the BDC firing angle are controlling to be the
same always.
[0015] In addition, because the TDC and BDC cannot be independently
controlled, the size of the stroke of the reciprocating compressor
cannot be maximized, failing to obtain maximum compression
efficiency.
SUMMARY OF THE INVENTION
[0016] Therefore, an object of the present invention is to provide
an apparatus and method for controlling an operation of a
reciprocating compressor capable of enhancing efficiency of the
reciprocating compressor by controlling a top dead center (TDC) so
as to fit a pre-set position and independently controlling the TDC
and a bottom dead center (BDC) so as to make the BDC fit a desired
position.
[0017] To achieve these and other advantages and in accordance with
the purpose of the present invention, as embodied and broadly
described herein, there is provided an apparatus for controlling an
operation of a reciprocating compressor including: a TDC/BDC
detecting unit for detecting a TDC and a BDC of the reciprocating
compressor; and a controller for independently controlling the TDC
and the BDC so as to fit each reference position based on the
detected TDC and BDC.
[0018] To achieve the above object, there is also provided a method
for controlling an operation of a reciprocating compressor
comprising: detecting a TDC and a BDC of a piston of the
reciprocating compressor; and independently controlling the TDC or
the BDC of the piston of the reciprocating compressor so as to fit
first and second reference positions, respectively.
[0019] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention.
[0021] In the drawings:
[0022] FIG. 1 is a block diagram showing an apparatus for
controlling an operation of a reciprocating compressor according to
the related art;
[0023] FIG. 2 is a block diagram showing an apparatus for
controlling an operation of a reciprocating compressor according to
the present invention;
[0024] FIG. 3 is a flow chart showing a method for controlling the
operation of the reciprocating compressor according to the present
invention; and
[0025] FIG. 4 is a graph showing a size of a stroke according to
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The apparatus and method for controlling an operation of a
reciprocating compressor capable of improving efficiency of a
reciprocating compressor by controlling a top dead center (TDC) and
independently controlling the TDC and a bottom dead center (BDC) to
make the BDC fit a desired position according to the present
invention will now be described with reference to FIGS. 2 to 4.
[0027] First, power mentioned hereinafter is, for example, 220V 60
Hz. Preferably, the apparatus and method for controlling an
operation of the reciprocating compressor does not include a
capacitor matched to a reactance of a motor of the
reciprocating.
[0028] FIG. 2 is a block diagram showing an apparatus for
controlling an operation of a reciprocating compressor according to
the present invention.
[0029] As shown in FIG. 2, the apparatus for controlling an
operation of a reciprocating compressor includes: a TDC/BDC
detecting unit 21 for detecting a TDC and a BDC of a reciprocating
compressor; and a controller for independently controlling the TDC
and the BDC so as to fit each reference position based on the
detected TDC and BDC.
[0030] The controller controls the TDC to fit the first reference
position based on the detected TDC and BDC and then controls the
BDC to fit a second reference position.
[0031] The controller independently controls a TDC firing angle and
a BDC firing angle to make the TDC fit the first reference position
and the BDC fit the second reference position.
[0032] The controller controls the BDC to fit the second reference
position based on the detected TDC and BDC and then independently
controls the TDC to fit the first reference position.
[0033] The controller controls the TDC to fit the first reference
position based on the detected TDC and BDC, and at the same time,
independently controls the BDC to fit the second reference
position.
[0034] The controller includes voltage and current detection units
22 and 23 for detecting voltage applied to the reciprocating
compressor and current flowing at the reciprocating compressor; a
microcomputer 24 for calculating a stroke estimate value based on
the detected voltage and current, and outputting a switching
control signal based on a result obtained by comparing the
calculated stroke estimate value and a stroke command value; and a
switch 25 switched on or off according to the outputted control
signal to control the TDC or BDC.
[0035] The reference position is previously set in the form of a
look-up table in a storage unit (not shown) by a user or previously
stored in a storage unit (not shown) after being calculated by the
microcomputer.
[0036] The switch 25 is a thyrister that controls current according
to the switching control signal and input AC power.
[0037] The operation of the apparatus for controlling an operation
of the reciprocating compressor according to the present invention
will now be described in detail.
[0038] FIG. 3 is a flow chart showing a method for controlling the
operation of the reciprocating compressor according to the present
invention.
[0039] As shown in FIG. 3, the method for controlling an operation
of the reciprocating compressor according to the present invention
includes: detecting a TDC and a BDC of a piston of a reciprocating
compressor (a first step, step S31); and independently controlling
the TDC and the BDC of the piston of the reciprocating compressor
to fit the first and second reference positions, respectively (a
second step, steps S32 and S33).
[0040] The second step (steps S32 and S33) includes reducing the
TDC firing angle and the BDC firing angle when the TDC does not fit
the first reference position.
[0041] The second step includes: first controlling the TDC of the
piston of the reciprocating compressor so as to fit the first
reference position (step S32); and controlling the BDC of the
piston so as to fit the second reference position, when the TDC of
the piston fits the first reference position (step S33).
[0042] In the second step, when the BDC does not fit the desired
position, the TDC firing angle is increased and the BDC firing
angle is reduced.
[0043] The second step includes: a first TDC control step of first
controlling the TDC of the piston of the reciprocating compressor
so as to fit the first reference position; and a first BDC control
step of controlling the BDC so as to fit the second reference
position, when the TDC of the piston fits the first reference
position.
[0044] The second step includes: a second BDC control step of first
controlling the BDC of the piston of the reciprocating compressor
so as to fit the second reference position; and a second TDC
control step of controlling the TDC of the piston so as to fit the
first reference position, when the BDC of the piston fits the
second reference position.
[0045] The second step includes: a third TDC control step of
controlling the TDC of the piston of the reciprocating compressor
so as to fit the first reference position; and simultaneously and
independently controlling the BDC of the piston so as to fit the
second reference position.
[0046] The TDC and the BDC values have values which are in inverse
proportion to the size of the TDC and BDC firing angles. Namely,
when the TDC firing angle is increased and the BDC firing angle is
reduced, the TDC value is reduced and the BDC value is increased,
in inverse proportion to the size of the respective firing angles.
Conversely, when the TDC firing angle is reduced while the BDC
firing angle is increased, the TDC value is increased and the BDC
value is reduced, in inverse proportion to the size of the
respective firing angles.
[0047] Referring to the relationship between the TDC and BDC firing
angles, the value of the BDC firing angle being reduced is smaller
than the value of the TDC firing value being increased.
[0048] In the step of making the TDC fit the first reference
position, the TDC is controlled to be zero (0).
[0049] The method for controlling an operation of the reciprocating
compressor will now be described in more detail as follows.
[0050] The TDC and BDC detecting unit 21 detects the TDC and the
BDC of the piston of the reciprocating compressor (step S31).
Herein, the TDC and BDC can be detected through various methods
which would not be described in detail herewith.
[0051] Next, the microcomputer 24 controls the TDC to be in a
pre-set position, preferably, to be zero (0) (TDC=0) while
monitoring the detected TDC in real time (step S32). Namely, the
microcomputer 24 calculates the stroke estimate value of the
reciprocating compressor based on the voltage and current detected
by the voltage and current detecting units 22 and 23, compares the
calculated stroke estimate value and a stroke command value, and
outputs a switching control signal to make the TDC of the piston of
the reciprocating compressor zero (TDC=0) based on the comparison
result and the detected TDC. Accordingly, by turning on or off a
switch (e.g., a triac) according to the switching control signal,
the TDC of the piston of the reciprocating compressor can become
zero (TDC=0).
[0052] In this case, if the TDC is not zero, the TDC and BDC firing
angles are reduced to increase the TDC. Namely, according to the
method for controlling an operation of the reciprocating compressor
of the present invention, the TDC which increases according to the
reduction of the TDC firing angle is controlled to be zero
(TDC=0).
[0053] When the TDC is zero, the microcomputer 24 controls the BDC
so as to fit a desired position while monitoring the detected BDC
in real time (step S33). Namely, the microcomputer 24 calculates
the stroke estimate value of the reciprocating compressor based on
the voltage and current detected by the voltage and current
detecting unit 22 and 23, compares the calculated stroke estimate
value and the stroke command value, and outputs the switching
control signal to make the BDC of the piston of the reciprocating
compressor position at a desired position based on the comparison
result and the detected BDC. Accordingly, the switch (e.g., the
triac) can be turned on or off according to the switching control
signal to make the BDC of the piston of the reciprocating
compressor come at the desired position. Herein, the desired
position is determined by a size of the stroke according to the
stroke command value.
[0054] In this case, if the BDC is not at the desired position, it
is increased by increasing the TDC firing angle little by little
and reducing the BDC firing angle. Namely, according to the method
for controlling an operation of the reciprocating compressor in the
present invention, the BDC which is increased according to the
reduction of the BDC firing angle is controlled to reach the
desired position. Herein, preferably, the TDC firing angle being
increased is smaller than the BDC firing angle being reduced.
[0055] When the BDC reaches the desired position, the TDC and BDC
firing angles at the time are maintained (step S34).
[0056] The size of the stroke according to the apparatus and method
for controlling an operation of the reciprocating compressor
according to the present invention is shown in FIG. 4.
[0057] FIG. 4 is a graph showing a size of the stroke according to
the present invention.
[0058] As shown in FIG. 4, the apparatus and method for controlling
an operation of the reciprocating compressor of the present
invention can increase the size of the stroke so as to be larger
than that of the related art.
[0059] As the present invention may be embodied in several forms
without departing from the spirit or essential characteristics
thereof, it should also be understood that the above-described
embodiments are not limited by any of the details of the foregoing
description, unless otherwise specified, but rather should be
construed broadly within its spirit and scope as defined in the
appended claims, and therefore all changes and modifications that
fall within the metes and bounds of the claims, or equivalents of
such metes and bounds are therefore intended to be embraced by the
appended claims.
* * * * *